This invention relates to a ski binding for use in mountain and/or cross country skiing. It should be noted that ski bindings for such mountaineering and cross country uses differ substantially from ski bindings used for downhill skiing in which the ski boot is held in fixed relation at both heel and toe to the ski member. In cross country and mountaineering skiing, the ski binding is of a different type in that the ski boot is required to have pivotal movement in relation to the ski member so that the ski boot and foot therein may propel the ski forwardly. Further, ski bindings for mountaineering purposes are different from cross country ski bindings in that mountaineering ski binding is used with rigid soled boots which are necessary for rock climbing, peak scaling, and ice climbing as with crampons. Cross country conventional ski boots are usually flexibly soled and will bend with the foot, but are useful only for cross country skiing and for walking. Mountaineering ski bindings used for high mountain travel must function with a skier who may carry heavy loads over steep up and down hill terrain. This requirement necessitates a means for lifting the heel from the ski to achieve forward motion in either "walking" or climbing.
The heel lifting function of a mountaineering ski binding has been facilitated by a hinge or pivot provided at the toe of the boot just slightly forwardly of the boot sole. The hinge may include a forward section which is secured to the top surface of the ski and an aft section which may comprise a long plate to which the boot is attached in a variety of ways. These bindings usually include some type of release mechanism for disengagement in the event of undue stress, as in a fall, and also include a device to lock the aft section of the plate or heel in downward position for added control in descending a hill. Such prior proposed existing devices have disadvantages in which the location of the pivot axis of the hinge forwardly of the toe of the boot causes a great deal of friction between the skier's heel and heel cup of the boot which, after many forward motions or strides, results in serious blisters of the heels of the skier. Attempts to compensate for this condition include tying the boots tighter to reduce the relative movement between the heel and the boot. Such tight bindings reduces circulation and in some circumstances invites frost bite. Another disadvantage of the prior proposed bindings relates to the motions required to lift the heel for forward propulsion, such motions being not bio-dynamically efficient and which lead to fatigue and sore calf muscles.
An example of such prior proposed devices is disclosed in U.S. Pat. No. 4,178,013 which is directed toward providing a ski binding to eliminate use of a rigid ski boot and to enable the skier to wear non-rigid boots. Ski bindings having pivotal axes forwardly of the toe of the ski boot are shown in Swedish patent No. 115,026, and Norwegian patent No. 28,871 which shows a ski binding device at the front portion of the boot for providing a pivot axis at the sole of the boot and in close relation to the top surface of a ski member Norwegian patent No. 67,729 shows a ski binding device having a pivot axis forwardly of the toe of the boot and having side links connected to the sole of the boot rearwardly of the toe of the boot.
In the conventional ski mountaineering binding used with a rigid soled boot, in order to step forward on one foot a force at the heel must be countered by an equal force located at an instep area due to the flexing of the boot material, compression of the socks, and flexing of the foot itself. As a result of this force relationship, the skier's heel within the boot will lift and rub against the inside surface of the boot heel cup causing blisters. The distribution of weight is such that most of the weight is at the fulcrum axis which, in the conventional mountaineering binding, occurs just forwardly of the front toe portion of the sole.